Field of the Invention
The present invention relates to an electron microscope specimen holder and, more particularly, to an electron microscope specimen holder which enables the specimen position to be stable even if heated and cooled.
When observing a specimen and performing various measurements (e.g., elemental analysis using characteristic X-rays) with an electron microscope, in order to prevent contamination of the specimen or induce the phase change, generally the specimen is observed and measured in a heated or cooled state.
As the temperature is elevated or lowered, the specimen position is changed due to thermal expansion or contraction of the holder, and accurate observation and measurement will be difficult. To cope with this, there a number of specimen or sample holders have been proposed.
In a first type of specimen holder disclosed, for example, in U.S. Pat. Nos. 3,896,314 and 4,703,181 the holder is constructed of plural materials whose thermal expansion coefficients are different from each other and they expand (shrink) in opposite directions so that a net shift of specimen (sample) position caused by thermal expansion is cancelled.
In a second type disclosed, for example, in Japanese Patent Unexamined Publication No. 1,197,952 (A), the temperature change of the specimen holder is detected by a sensor and a specimen support is moved in an amount corresponding to the thermal expansion so as to maintain the specimen position unchanged, thereby enabling accurate observation or measurement.
The first type conventional approach is based on an assumption that a uniform temperature distribution can be obtained over a wide area. In real sample (specimen) holders, however, thermal conduction of various materials is important and there exist temperature profiles which change in various forms, resulting in an error of the specimen position.
In the second type conventional approach, the actual position change of the specimen is not detected, and it is not easy to maintain the specimen position unchanged.
Further, in any case, no consideration has been given to the accurate rotation about a tilt axis or axes of the specimen, particularly the tilt axis perpendicular to the axis of the specimen holder.
As described above, the prior art involve the problem that it is difficult to maintain the specimen position unchanged, in the heating specimen holder accompanied with parallel movement and rotary driving.